Brown rice question

I know that brown rice doesn't last forever in storage, because the oils in the rice react with air and go rancid eventually.

Would packing the rice in dry ice help with that?

Mylar bags and O2 absorbers would help I believe.

It will still go rancid. The oils will spoil eventually regardless. Packing in Mylar with o2 absorbers and freezing it seems to be the best way to extend shelf life, but even then, you're only looking at a few years.